The present invention relates generally to an antenna, and more particularly to an antenna for transmitting or receiving signals to or from one or more satellites.
For many years, satellite communication systems were typically used only in industrial and military applications, with little use in the general private sector. However, in recent years, there has been a significant increase in the amount and types of information that is transmitted via satellite communication for individual consumer use. For instance, satellites now transmit telephone signals, television signals, and Internet data, etc. Due to the increased amount of information and services offered via satellite communication for individual consumer use, there has been an associated need for antennas designed with the individual user in mind.
Specifically, many of the antennas used for commercial and military-based applications are typical large structures having large aperture reflectors and rather large, high power transmitters. As private sector antennas are used mainly in residential setting, the size and associated cost of these large aperture antennas generally make them impractical for individual consumer applications. As such, as satellite communication continually moves to the private sector, there exists an increased need to provide antennas that are both compact and aesthetically pleasing for residential installation.
For this reason, small aperture antennas have been developed that use smaller reflector configurations and smaller transmitters. These small aperture antennas are generally small enough to be used in residential settings. They are also typically cost effective. However, many current small aperture antenna designs, have some drawbacks that may not only unnecessarily increase their size but may also increase stress in the antenna structure.
For example, FIG. 1 illustrates a typical antenna system 10 used to establish communication with a satellite. The antenna system includes a reflector 12 for directing at a satellite, not shown, to receive signals from the satellite and provide these signals in a focused manner to a feed 14 positioned in front of the reflector. Further, the reflector may also direct signals from the feed to the satellite. The reflector is connected to the ground or other type of stationary structure by a mounting post 16, and the feed 14 is connected to the reflector via a boom arm 18. Importantly, the antenna also includes electronics 20 such as a low noise block and/or transmitter connected to the feed. The low noise block is used to filter and amplify signals received by the feed from the satellite prior to application to a receiver unit. Further, the transmitter provides signals to the feed for transmission to the satellite.
As illustrated in FIG. 1, a drawback with many antenna designs is that the transmitter and/or receiver components 20 are typically placed in an in-line configuration behind the feed 14. This in-line configuration may result in an enlarged component packaging for the antenna. In other words, the distance D between the reflector 12 and the distal portion of the antenna opposite the reflector is increased by the placement of the transmitter and/or receiver electronics in an in-line configuration behind the feed. This, in turn, may not only increase the size of the antenna but may also decrease the aesthetic value of the antenna.
An additional problem with the conventional antenna design illustrated FIG. 1 is that the in-line configuration of the transmitter and/or receiver may also increase the load on the boom arm and mounting post of the antenna. Specifically, the further the distance D the transmit and receive electronics are from the reflector, the greater the moment force M on the boom arm 18 and mounting post 16. These moment forces may cause stress in the boom arm and mounting post structures and under some conditions, such as high winds or heavy snow, may cause failure. In light of this, an antenna having a more compact configuration may be desired, not only for private sector use, but also for industrial and military applications.
As set forth below, the present invention provides various antennas, support apparatus, and wave-guides that overcome many of the identified deficiencies and several additional deficiencies associated with providing an antenna having a compact configuration and decreased moment stress on the antenna structure. According to the present invention, an antenna is provided having a compact feed structure such that either one or both the receiver and transmitter electronics associated with the antenna are more closely spaced with respect to the reflector of the antenna. This compact structure may decrease the overall size of the antenna and also reduce moment forces on the boom arm and mounting post of the antenna.
Specifically, in one embodiment, the present invention provides a novel wave-guide design used for connecting the feed of an antenna to various electronics, such as a transmitter or receiver. The wave-guide of this embodiment includes a first end for connecting to the feed and a second end for connection to either a transmitter, receiver, or other electronic components. Importantly, the body of the wave-guide extends in a direction towards the reflector of the antenna so that the second end of the wave-guide is positioned closer to the reflector than the first end of the wave-guide. As such, the transmitter or receiver that is connected to the second end of the wave-guide is located in closer relationship with the reflector, thereby creating a compact, aesthetically pleasing antenna structure. Further, because the transmitter or receiver is located proximal to the reflector, the moment forces on the mounting post and boom arm of the antenna are reduced over prior art antenna designs.
For example, in one embodiment of the present invention, the feed of the antenna has a proximal end directed at the reflector of the antenna and a distal end directed away from the reflector of the antenna. In this embodiment, the first end of the wave-guide of the present invention has an end surface oriented toward the reflector for connecting to the distal end of the feed. The end surface of the wave-guide defines a plane which is spaced forwardly of the reflector. In this embodiment, at least a portion of the body of the wave-guide extends towards the reflector and is projected beyond the plane. More specifically, in one embodiment, the second end of the wave-guide projects beyond the plane.
In one embodiment, to make the antenna more compact, the body of the wave-guide of the present invention extends along an axis of extension at an offset angle that is less than 90 degrees with respect to an axis extending between the proximal and distal ends of the feed. This angle of offset directs the second end of the wave-guide back toward the reflector, such that the transmitter or receiver connected to the second end of the wave-guide is proximal to the reflector.
In another embodiment, the wave-guide of the present invention has a body with two sections. Specifically, the first body portion of the wave-guide is connected to the feed by the first end of the wave-guide. The first body portion has an axis of extension such that the first body portion extends from the first end of the wave-guide at a first offset angle with respect to an axis extending between the proximal and distal ends of the feed. At the end of the first body portion of the wave-guide is a bend portion. Connected to the bend portion is a second body portion that has a second axis of extension. This second axis of extension extends at a second offset angle from the first axis of extension of the first body portion towards the reflector of the antenna.
As an example, in one embodiment, the first body portion of the wave-guide of the present invention extends from feed at a first offset angle of 90 degrees. Further, in this embodiment of the wave-guide of the present invention, the second body portion of the wave-guide extends along a second axis at an offset angle with respect to the first body portion at angle in the range of greater than 0 degrees and less than 180 degrees. In this configuration, the second end of the wave-guide is closer to the reflector of the antenna than the first end of the wave-guide. As such, any electronic component connected to the second end of the wave-guide, such as a transmitter or reflector, are proximate to the reflector.
As mentioned above, the wave-guide of the present invention can be used as either a transmit or receive wave-guide depending on the particular application. For example, in one embodiment of the present invention, the wave-guide is a receive wave-guide having a first end connected to the feed and a second end connected to a receiver, such as a low noise block. As before, in this embodiment, the second end of the wave-guide extends toward the reflector of the antenna, such that the receiver is located proximal to the reflector. In an alternative embodiment, the wave-guide of the present invention is a transmit wave-guide with a transmitter connected to the second end of the wave-guide, such that the transmitter is proximal to the reflector of the antenna.
In some embodiments, the present invention further provides an apparatus for coupling at least one of a transmitter and a receiver to a feed of an antenna. The apparatus includes a support structure that has a first port for connection to the feed and a second port for connection to either a receiver or a transmitter. In this embodiment, the first end of the wave-guide of the present invention is connected to the second port of the support structure and the second end is connected to either a transmitter or receiver and extends toward the reflector of the antenna.
Importantly, in one embodiment, the feed associated with the support structure of the present invention is used for two-way communication with a satellite, such that the feed both receives signals from and transmits signals to the satellite. In this embodiment, the support structure of the present invention is an ortho-mode transducer capable of receiving signals from and providing transmit signals to the feed. The support structure of this embodiment of the present invention includes a first port for connection to the feed, a second port for connection with a transmitter, and a third port for connection to a receiver.
In this embodiment, the present invention further includes a transmit wave-guide connected between the second port of the support structure and a transmitter and a receive wave-guide connected between the third port of the support structure and a receiver. In this configuration, at least one of the wave-guides has a body that extends toward the reflector of the antenna such that at least a portion of the body of the wave-guide extends past the first end of the wave-guide to thereby position the transmitter or receiver connected to the wave-guide proximal to the reflector of the antenna. In one further embodiment, both the transmit and receive wave-guides extend toward the reflector of the antenna such that both the receiver and the transmitter are proximal to the reflector.
The present invention also provides an antenna that incorporates the wave-guide of the present invention. Specifically, according to one embodiment, the antenna includes a reflector and feed connected to each other by a boom arm. The antenna further includes a wave-guide having a first end connected to the feed and either a transmitter, a receiver, or other component connected to the second end of the wave-guide. The second end of the wave-guide extends toward the reflector such that the transmitter or receiver connected to the wave-guide is positioned proximal to the reflector. In this embodiment, because the transmitter or receiver is located proximal to the reflector, the moment forces on the boom arm connecting the feed to the reflector are reduced over prior art configurations.
In one advantageous embodiment, the antenna further includes either a transmitter or receiver connected to the boom arm of the antenna. In this embodiment, the wave-guide connecting the transmitter or receiver to the feed, extends from the feed to the wave-guide.